Duplex control of reservoir pressure



Y Mayf3lz, 1932.-

(ww l M. L. HANCOCK 1,860,414

DUPLEX CONTROL 0F RESERVOIR `PRESSURE Filed Oct. 16. 1950 INVEN TOR.

MILTON l.. HANCOCK BY vQmf A TTORNE Y.

Patented May 31, .19252` nNiriiEa'sr-Arrs MILTON In HANCOCK,-

EASTABICKEESIORT, PENNSYLVANIA, ASSIGNOR T THE WEST-l INGHOUSE AIR BRAKE CGMPANY, 'OFAWILMERDIN' PENNSYLVANIA, A CORPORA- il TION 01?A PENNSYLVANIA Y Y :DUPLEX con'rnor. or RESERVOIR rnnssnnn' Application led October .16, 1930. Serial No. 489,011.

VThis invention relates to pressure governors ofthe type particularly adapted tov control the operation of an electrically actuated fluid compressorin such a manner zor las to automatically maintain the pressure of fluid in a reservoir atl a predetermined, sub'-l stantially' constantyalue.

Under certain conditions of train operation, such as when the train brakes are released and the brake equipments are charged with duid under pressure, it is only necessary to carry a relatively low pressure inthe mainy provide improved means for so controlling the operation of a luid compressor as to main- `taina'certain predetermined pressure in a reservoir at one time, and for maintaining a 5. different predetermined pressure inthe reservoir atr another time.

In carrying out my invention,` I employ a highpressuregovernorr and a low pressure governor Vfor at dier'ent timesfcontrolling the operation of `a 'Huid compressor. Both governors are of aswell knowntype employed for controlling the circuit through an electric motor and operate upon a predetermined increase in reservoiry pressure to stop the operation of the compressor and upon a predetermined decreasein .reservoir pressure to start ythe compressor operating, andin this manner cause the compressor to maintain the reservoirfpressure between fixed limits or at a predetermined substantially constant pressure, as hereinbefore mentioned.

In the accompanying-drawings; Figure 1 is a diagrammatic view, partly in section, `oit' a portion of a fluid vpressure controlY system embodying my invention; and Figj2 Ais a diagrammatic view of a portion of the brake valve deviceshown in Figgl, but having the rotary valve-in a different position.

As shown in therdrawings, the fluid presf sure controlsystem comprises a low pressure governor, a 'high' pressure governor, an elecv trically .operated fluid compressorl, a reser-y voir 2, and a brake valve device 3.

- The low pressnregovernor and high pres]-v sure kgovernor are Veach of the same construc-l tion and each comprises a switch portQn 4 v l and a regulating POFOn 5. The switch por:

tion 4 comprises a piston f6 having at one side a chamber 7 and at the other side a chamber 8 and provided with astem 9, carrying atits outer end connected switch contacts 10 adapted to bridge two xed contacts 11 andy 12 for closing an'electric circuit. A spring 13'is contained in the chamber Sffor urging Y the pistonV 6 to the cut-in position as shown in the drawings. Y

The regulating portion 5 of the governors comprises a cut-in piston 14 having at oneend a valve 15 and subjectto the pressure of an adjustable coil spring 16, and a cut-out piston 17 having at one end a valve 18 and subject to the pressure of an adjustable coil spring 19.n

The' electrically operated fluid compressor 1 may be of any well known construction comprising a compressor portion 2O for supply,-

ing. fluid underpressure to the reservoir 2y and an electric motor 21 for operating the compressor.

The brakevalve device 3 is of the 'usual con'- struction comprising a casing having a 'chamber 22 containing a rotary valve 23 adapted to be turned to various positionsby means of a handle 24, .Y

In operation, it is Vassumed that the adjustable springsA 16 and 19 of the governors are adjusted Ato theV desired, predetermined cutting-in and cutting-out pressures. Forexample, the cut-'in valve spring 16 ofthelow pressure governor is so adjusted as to seat the cut1n valve 15 against an opposing reservoir pressure `of pounds acting onthe cut-fink piston 14,1 and thecut-out valve spring 19 is so adjusted as to maintain the cutout-valvev 18 seated until the reservoir pressure is'in creased to pounds. In the high pressure governor, the adjustment of the cut-in valve spring may be-l30 pounds, and of the cut-out valve spring pounds; It will be lnoted that the adjustment of the'cut-in valve spring and output valve spring of the two governors is yso arranged thatthe lcut-out pressurev `of the low pressure governor is lower than the cut-in pressure of the high pressure governor, so that there will be no overlapping of the operating pressures of the governors, which would interfere in the desired operation.

Fluid under pressure from the reservoir 2 Hows through pipe 24 to passage 25 in the high pressure governor and to valve chamber 22 in the brake valve device 3. With the brake valve device in the running position shown in Fig. 1 of the drawings, fluid at reservoir pressure flows from valve chamber 22 through port 26 in the rotary valve 23 to passage 27, which is connected through pipe 28 with passage in the low pressure governor.

Fluid under pressure supplied to passage 25 in the low pressure governor and iii the high pressure governor flows therefrom through a passage 29 to the seated area of the cut-in valve 15 and from passage 25 through chamber 30 to the seated area of the cut-out valve 18. n

Assuming the reservoir pressure to be less than the adjusted cutting-in pressure of the cut-in valve spring 16 of the low pressure governor, the cut-in valve 15 and cut-out valve 18 of both governors will be seated and the piston chamber 7 of each governor will beconnected to the atmosphere through passage 31, groove 45, and ports 32 in the cutout piston 17 chamber 33, passage 34, past the end of the cut-in piston 14, chamber 35 and atmospheric port 36. With the piston chamber 7 at atmospheric pressure, the pressure of spring 9 in each governor holds the piston 6 in the position shown in the drawings in which the contacts 10 engage the fixed contacts 11 and 12 which closes a circuit from a source of current, such as a trolley wire 37, through the compressor motor 21 by way of wire 3,8, contacts 12, 10 and 11 of the low pressure governor, wire 39, contacts 12, 10 and 11'of the high pressure governor, wire 40 to the compressor motor and ground 41.

With the circuit closed through the electric motor 21, the compressor 20 is operated to supply fluid under pressure to the reservoir 2, which increases the pressure of fluid acting on the cut-in valve 15 and cut-out valve 18 of the high pressure governor and of the low pressure governor, the brake valve device 3 being in running position, as shown in the drawings, in which communication is established to the low pressure governor.

In both governors the seated area of the cut-out valve 18 is greater than the seated area of the cut-in valve 15. The cut-out valve spring 19 of the high pressure governor is of greater value than the corresponding spring in the low pressure governor, so that when the reservoir pressure acting on the seated area. of the cut-out valve 18 of the low pressure governor is built up suflicient to overcome the pressure of spring 19, the cut-out valve is moved away from its seat. This permits fluid at reservoir pressure to flow through passage 42 to chamber 43 and therein su plement the reservoir pressure acting on t e valve 15 and shift the cut-in piston 14 to its seat 43. With the cut-in piston 14 of the low pressure governor engagin seat 43, fluid at reservoir pressure flows rom passage 25, through passage 29, chamber 43 and passage 34 to the cut-out piston chamber 33, thereby balancing the pressure of 'luid acting on the opposite ends of cut-out piston 17, which permits spring 19 to shift said piston back to its normal position and thus seat valve 18.

When t-he cut-out piston 17 is moved back to its normal position, the annular groove 45 in the cut-out piston registers with the passage 31 and fluid under pressure is permitted to llow from chamber 33 through the ports 32, groove 45, and passage 31 to switch piston chamber 7. The pressure of fluid in chamber 7 shifts the piston 6 upwardly, com pressing spring 13 and moving the contacts 10 out of engagement with the contacts 11 and 12. The circuit through the compressor motor is thereby opened, which causes the compressor 20 to stop.

Vhen the pressure of lluid in reservoir2l and acting on the full exposed area'of cut-in` piston 14 is reduced sutlicient to be overcome by the pressure of the spring 16, the cut-1n piston 14 is moved away from its seat 43, which permits fluid under pressure to How to the cut-in piston spring chamber 35 by way of passage 42, annular groove 47 in the cutout piston 17, passage 48 andpassage 49. The rate of flow to the cut-in piston spring chamber 35 exceeds the ventinnr capacity of the atmospheric port 36, thereby causing a pressure to be built up on piston 14 which aids spring 16 in moving'the piston 14 so as to seat the valve 15. Fluid under pressure is then vented from the piston chamber 7 through passage 31, annular groove 45 in the cut-out piston 17, ports 32, chamber 33, passage -34, chamber 35, and atmospheric port 36, which permits spring 13 to shift the piston 6 downwardly and move contacts 10 into engagement with contacts 11 and 12. The circuit through the compressor motor is thus closed and the compressor is then operated to build up the pressure in the reservoir 2.

It will be noted the high pressure governor does not operate when the low ressure governor is controlling because the igh pressure governor is adjusted for higherk pressures than the low pressure governor permits to be obtained.

If it is desired to have a higher pressure in the reservoir 2 than permitted by the con-y trol of the low pressure governor, the brake valve device 3 is turned to another position, such as service or lap position, as shown in Fig 2 of the drawings, in which position the fluid pressure supply pipe 28 to the low pressure governor is connected to the atmosphere through Vpassage 27, cavity 48 in the rotary valve 23 and atmospheric passage 49. vBy

dered ino erative and the high ressure Governor connected directly td the reservoir 2,

Vthe high pressure governor will operate to control the pressure in said reservoir in the samemaner as the low pressure governor, but since the contol springs 19 and 16 in the high pressure governor are of a higher adjusted value than the corresponding springs in the low pressure governor, the reservoir pressure required to operate the high pressure governor to cut-out position will be higher than required to operate the low pressure governor to cut-out position andthe pressure at which the high pressure governor will operate to cut-in position will also be higher.

It will be noted that the compressor circuit is at all times Acontrolled'through the switch contacts of both governors, but-that the regulating portions 'operate independently of each other in accordance with the position of the brake valve device 3.

A reservoir is connected by a branch pipe 51 to the low pressure governor supply pipe 28 for the purpose of increasing the voldevice.

ume of fluid under pressure acting onthe Vlow pressure governor cut-in valve 15 and cut-out valve 18,*so as to 'stabilize the pressure acting on ysaid valvesk against possible fluctuations in theA pressure of fluid inthe rotary valve chamber 22 ofthe brake valve This is not necessary in thecasek of the high pressure governor since the reservoir 2 is direct-ly connected thereto.

While one illustrative embodiment of ther inventionhas been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by thev terms of the appended claims. Y

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

V1. The combination with `a reservoir, a

compressor for supplying fluid under presi Y sure to said reservoir, and a motor for operating said compressor, of two switches arranged in series in the circuit of said motorfor controlling said circuit, a pair of governors, each operative by the pressure of fluid ,in said reservoirfor controllingone of lsaid switches and means for cutting one governor intoy action .when the-other governor is cut out ofaction.

2. The combination with a reservoir, a

Vcompressor for'supplying lfluid' under pressure to said reservoir, and a motor for operating saidcompressonof a pair of switches connected'in series and independently operative to 'control the circuit of said motor, .a

governor for each of said switches controlled to one of said governors forrenderingit inoperative. Y

il. The combination with a reservoir, a compressor for supplying fluid-under pressure to said reservoir, and ainotor for operating said compressor, of a pair of governo-rs each subj ect to the pressure of fluid in said reservoir for controlling the electric circuit of said motor, andvalvemeans for controlling the supv n of fuid from said reservoir to one of said governors and havingva position for cutting off' said supply for rendering the last men-Y tioned governor inoperative to control said circuit. I

5. The combination with a reservoir, a compressor-for supplying fluid under pressure to said reservoir, and a motor for operatingvsaidcompressor, of a high pressure governoi' subject to the pressure of fluid in said reservoir for controlling the circuit of said motor, a low pressuregovernor cooperative with said high. pressure governor for closing said circuit and operative by uid under pressure supplied from saidreservoir to open said circuit, and valve means for cutting off the supply of fluid under pressure to said-low pressure' governor for rendering ysaid low pressure governor'inoperative `to open said circuit. Y

6. The combination with a reservoir, a compresser for supplying fluid under pressure to said reservoir, and an electric motor for operating said compressor, of a high pressure governorand a low pressure governor cooperative with each other at one time for closing the circuit of said motor, and operative independently of each otherk at another time in accordance with the pressure of fluid in said reservoir for opening said circuit, and valvev vmeans for controlling` communication from said low pressure governor to said reservoir and having a position for closing said communication and opening an atmospheric 'connection yto said low pressure governor for rendering said lowfpressure governor inoperating saidk compressor, of a high pressure governor and a low pressure governor coop- IOOf erative 'with each other at one time for closing the circuit of said motor, and operative independently of each other at another time in accordance with the pressure of fluid in said reservoir for opening said circuit, and valve means for controlling communication from said 10W pressure governor to said reservoir' and having a position for closing said n communication and permitting said 10W pressure governor to be subject to the pressure of the atmosphere for rendering said low pressure governor inoperative to open said circuit.

8.y The combination with a reservoir, a compressor for supplying fiuid under pressure to said reservoir, and an electric motor for operating said compressor, of a high pressure governor having a switch for opening and closing the cricuit of said motor, and a valve mechanism subject to the pressure of fluid in said reservoir for operating said switch to f open the motor circuit upon a predetermined increase in reservoir pressure and to close the motor circuit upon a predetermined decrease in reservoir pressure, a low pressure governor having a switch for opening and closing said motor circuit, and a valve mechanism subject at one time to the pressure of fiuid in said reservoir for operating the low pressure governor switch to open the motor circuit upon an increase in reservoir pressure to a degree less than that at which the high pressure governor operates to close the motor circuit, and operative upon a decrease in reservoir pressure to close the motor circuit, said 10W pressure governor valve mechanism being subject at another time to atmospheric pressure for rendering it inoperative to open the motor circuit, and valve means for controlling communication from said 10W pressure governor to said reservoir and to theY atmosphere.

In testimony whereof I have hereunto set my hand, this 13th day of October, 1930.r

MILTON L. HANCOCK. 

